Composite structure joining system and method and related structures

ABSTRACT

A composite structure joining system and method comprises a structural panel, preferably but not necessarily fabricated from structural composite materials, that further comprises a nesting C-joint feature that facilitates assembly of a plurality of panels of the invention to form a planar structure such as a wall. An embodiment of the present invention comprises a plurality of the panels of the invention, joined together using the C joint of the invention, captured in a frame. The frame structural elements may comprise metals such as aluminum or steel, or may be hand laid or extruded fiberglass as described in more detail below. The invention further comprises methods of manufacturing a plurality of structural panels of the invention. The method of the invention may be used to fabricate intermodal shipping containers that have superior structural and thermal characteristics, are lightweight, resulting in lower transportation costs and lower container costs.

CROSS REFERENCE TO RELATED APPLICATIONS AND INCORPORATION BY REFERENCE

This patent application claims benefit of priority to United Statesprovisional patent application Ser. No. 62/195,948 titled COMPOSITESTRUCTURE JOINING SYSTEM AND METHOD AND RELATED STRUCTURES filed in theUnited States Patent and Trademark Office (USPTO) on Jul. 23, 2015,which is incorporated herein its entirety by reference.

This patent application also incorporates by reference in their entiretyeach of the following patents and printed patent publications: U.S. Pat.No. 9,371,468, titled CO-CURED GEL COATS, ELASTOMERIC COATINGS,STRUCTURAL LAYERS, AND IN-MOLD PROCESSES FOR THEIR USE, which issuedfrom the USPTO on Jun. 21, 2016; United States printed patentpublication number US2014-0262011 A1, titled STRUCTURAL COMPOSITEPREFORM WET-OUT AND CURING SYSTEM AND METHOD, published by the USPTO onSep. 18, 2014; U.S. Pat. No. 6,543,469, titled SYSTEM FOR CONTINUOUSLYMANUFACTURING A COMPOSITE PREFORM to Lewit et al., (“the '469 patent”),which issued from the USPTO on Apr. 8, 2003; U.S. Pat. No. 5,897,818,METHOD FOR CONTINUOUSLY MANUFACTURING A COMPOSITE PREFORM to Lewit etal., which issued from the USPTO on Apr. 27, 1999; U.S. Pat. No.6,013,213 titled METHOD FOR MAKING DEFORMABLE COMPOSITE STRUCTURES ANDASSEMBLING COMPOSITE ARTICLE, which issued from the USPTO on Jan. 11,2000; U.S. Pat. No. 5,429,066 titled COMPOSITE STRUCTURES AND METHOD OFMAKING COMPOSITE STRUCTURES, which issued from the USPTO on Jul. 4,1995; and U.S. Pat. No. 5,908,591 titled METHOD FOR MAKING COMPOSITESTRUCTURES, which issued from the USPTO on Jun. 1, 1999.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISK

Not applicable.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The field of the invention relates generally to composite structuremanufacture and assembly of structures that may be used, for example, inapplications such as refrigerated box structures as may be used fortransport of refrigerated goods. Refrigerated box structures may beutilized in over the road trucking or rail shipping and are but oneexample of the many applications that derive benefit from the presentinvention. The composite structure and method of fabrication of theinvention is also useful for building wall panel construction in thebuilding construction trades, enclosure structure construction and otherstructural applications. The composite structure joining system andmethod of the invention provides significant improvements over the stateof the art by enabling the joining of panel structures, which may, butdo not necessarily, comprise structural composite materials, that areable to withstand greater impact than assembled panel structures of theprevious art, are easier to assemble and may result in faster productionrun rates, are significantly more thermally efficient than structures ofthe prior art, and result in longer life, lower maintenance costs, andoverall lower cost of operation over time than assembled panelstructures of the prior art.

2. Background of the Invention

Structures that comprise an assembly of panels, such as walls, havenumerous and varied applications in a number of industries. For example,buildings, shipping containers, retaining walls, and numerous otherstructures may be designed and fabricated based upon the use of panelsin their construction. Such panels may have certain desired structural,thermal, weight, electrical insulation, corrosion resistance or otherdesired physical or chemical characteristics that are may determine thesize and configuration of the panel, and may (and often does) determinethe selection of material used to fabricate the panel. Typically,depending upon the application, panels may be pre-fabricated and formedinto a desired shape such as in the case of a shipping container or incertain construction projects; or, in the alternative, panels may befabricated in situ if desired in certain construction projects or otherstructural applications.

As a specific example, containers for use in intermodal shipping aretypically rectangular in shape and are constructed of metal, typicallysteel, and are fabricated by welding or other mechanical assembly meansknown in the art. Such metal containers, when used in refrigeratedshipping applications, require additional thermal insulation and maynever in fact be well insulated due to the selection of materialstypically used to fabricate them. The result may be that increased meansof active cooling may be required in such applications. Such means mayinclude water cooling systems as may be used on ships, or additionalrefrigeration units powered by diesel generators used in over the roadtrucking applications. However, the use of additional refrigeration mayresult in lower reliability, higher fuel and equipment costs, andoverall higher cost to ship refrigerated products.

One reason for the use of metals, and specifically steel, in intermodalshipping container construction is that shipping containers may besubjected to various steady state or impact loads such as fork liftimpact or dropping of the container, all while carrying heavy cargoinside. For this reason shipping containers are expected to be subjectedto years of such loading without failure. Thus, steel is a reasonablechoice from a structural point of view, but is heavy and is a poorthermal insulator.

Furthermore, transportation costs are generally directed related to fuelusage, which is in turn directly related to the weight of the productbeing shipped. It is therefore desirable that weight of an intermodalshipping container be kept as low as reasonably possible.

What is needed in the art of structure fabrication, then, is an impactresistant and load-capable structure comprised of materials andconstruction details that afford light weight and increased thermalinsulation properties that may be readily constructed in quantity sothat manufacturing costs are kept low.

BRIEF SUMMARY OF THE INVENTION

The present invention comprises a system and/or method that have one ormore of the following features and/or steps, which alone or in anycombination may comprise patentable subject matter.

The system and method of the invention described in detail belowcomprises a structurally robust, mass producible, structural compositepreform panel that further comprises features that enable accurateassembly, and of which a plurality may be assembled together to form aplanar or other formed structural surface such as a wall, which may thenbe used to constructive a thermally insulative, structurally robustcomposite structure. The panels of the invention may be mass produced sothat economies of scale are realized. The composite structure of theinvention is also corrosion resistant and light weight.

In accordance with one embodiment of the present invention, thecomposite structure joining system and method of the invention comprisesa structural panel, preferably, but not necessarily, fabricated fromstructural composite materials, that further comprises a C-joint featuredisposed on one or more of the panel side end faces that facilitatesassembly of a plurality of panels of the invention to form a compositestructure such as a wall. The structural panel of the invention may befabricated by any means known in the art, but specifically may bepreferably fabricated by use of the PRIZMA® method of fabricatingcomposite structures as described further below. An additionalembodiment of the present invention comprises a plurality of the panelsof the invention, joined together using for example the C-joint of theinvention described below in more detail, captured in a frame that maycomprise structural elements with a generally C-shaped cross-sectionwherein the frame surrounds the plurality of assembled panels on atleast one side but, preferably, in a rectangular panel configuration onall four sides. The frame structural elements may comprise metals suchas aluminum or steel, or may be hand laid or extruded fiberglass asdescribed in more detail below. The invention further comprises a methodof assembly of a plurality of structural panels of the invention. Themethod of the invention may be used to fabricate, for example and not byway of limitation, a wall or other flat structural element comprised ofa plurality of structural panels of the invention, such as may be usedto further fabricate an enclosed box structure that may be utilized, forexample, to create intermodal shipping containers that have superiorstructural and thermal characteristics, are lightweight, and able to beproduced in quantities such that economies of scale may be realized,resulting in lower transportation costs and lower container costs.

In an embodiment, the invention comprises a nested C joint between twoadjoining panels. The nested C joint between adjoining panels is formsfrom a first panel having a first edge, a first planar surface, and asecond planar surface, said first edge comprising a concave arcuatesurface; and a second panel having a second edge, a third planarsurface, and a fourth planar surface, said second edge comprising aconvex arcuate surface. The concave arcuate surface and said convexarcuate surface are complementary, and the concave arcuate surface isadapted to receive the convex arcuate surface such that when the firstedge of the first panel and the second edge of the second panel arebrought together, the concave arcuate surface and the convex arcuatesurface together form a nested joint between the first and secondpanels, and the first planar surface and said third planar surfacetogether form a resulting fifth planar surface, and the second planarsurface and the fourth planar surface together form a resulting sixthplanar surface.

In a further embodiment, the invention comprises a panel, which may beused, for example, as a panel or wall structure, which may have anyoutline shape desired, such as rectangular, square. The panel of theinvention comprises a first planar surface, a second planar surface, afirst edge comprising a C-joint having a concave arcuate shape, and asecond edge comprising a C-joint having a convex arcuate shape, whereinthe convex arcuate shape and concave arcuate shape are complementary andare adapted to be received by the edge of an adjoining panel of theinvention having a complementary arcuate shape, forming a nested jointbetween the adjoining panels. In further embodiments, the panels of theinvention may have other edges that may be adapted to nest with orattach to features in adjoining structures such as panels or otherstructural members. Such other adjoining structures may be, for example,and not by way of limitation, panels or other structural members thatmay form part walls or part of a top surface or bottom surface of anenclosure. Thus, the panels of the invention may be used to form, forexample, an enclosure. Such an enclosure may be, for example, anenclosure to be used for a refrigerated box for shipping refrigeratedgoods by truck, rail or other transport system. However, it isunderstood that composite structures comprising a C-joint of theinvention are applicable and adaptable to any structural applicationsuch as flooring, sound barriers, roofs structures or any otherapplication requiring a planar structure.

In still a further embodiment, the invention comprises a planarstructure formed of a plurality of adjoining panels, wherein each panelcomprises a first planar surface, a second planar surface, a first edge,and a second edge, each of said first planar surface, second planarsurface, said first edge and said second edge covered with a layer offabric; wherein the first edge of each of the plurality of panels isdefined as comprising a concave arcuate surface; and wherein the secondedge of each of the plurality of panels is defined as comprising aconvex arcuate surface; and wherein the concave arcuate surfaces arecomplementary to the convex arcuate surfaces and wherein the concavearcuate surface is adapted to receive the convex arcuate surface of anadjoining panel when the first edge of the first panel and the secondedge of the second panel are brought together, forming a nested jointbetween adjoining panels. Each panel of the plurality of panels isattached to an adjoining panel by a nested joint. The plurality ofpanels has a resulting third planar surface formed by the first planarsurfaces of each of the plurality of panels, and also has a resultingfourth planar surface formed by the second planar surfaces of each ofthe plurality of panels. Each of the layers of fabric is saturated witha resin that is subsequently cured.

In still a further embodiment, the invention comprises a method offabricating a planar structure, comprising the steps of 1) providing aplurality of panels, each panel comprising foam covered by fabric,wherein each panel of said plurality of panels comprises a first planarsurface, a second planar surface, a first edge, and a second edge, eachof said first planar surface, second planar surface, said first edge andsaid second edge covered with at least one layer of fabric; wherein saidfirst edge of each panel of said plurality of panels is defined ascomprising a concave arcuate surface in cross section; and wherein saidsecond edge of each panel of said plurality of panels is defined ascomprising a convex arcuate surface in cross section; 2) assemblingplurality of panels together forming a resulting planar structurecomprised of adjoining panels joined together at a nested joint in whichthe convex arcuate surface of one panel of said plurality of panels isnested into the concave arcuate surface of an adjoining panel of saidplurality of panels, said resulting planar structure having a resultingfirst planar surface and a resulting second planar surface; 3)saturating each of said layers of fabric with a resin; and 4) curingsaid resin.

The structural panels of the invention comprising a C-joint may beirregularly shaped or multi-sided panels, and the C-joint feature of theinvention may be used in any surface thereof, including but not limitedto planar panel surfaces and end face surfaces. In other words, it isnot necessary that the invention comprise only four sided, planarstructures.

The shape and dimensions of the invention are adaptable to manyapplications. Furthermore, the arcuate surface shape is referred toherein as a “C” shape, however in is within the scope of the inventionthat the arcuate surface shape may be any shape desired, the shape beingdetermined by desired structural and thermal properties of the assembledcomposite structure. For example, a deeper elongated C shape willprovide a different structural response than a shallower C shape, withless resistance to deforming transversely, but will tend to extend thesupporting effect over a longer area of the panel. The specific shape ofthe joint may thus be optimized for a given loading conditions. Thinnerpanels would benefit from more frequent joints while thicker panels canhave the joints spaced over a greater panel span. The response of thepanel is also impacted by the laminate schedule. The fiber type, fiberorientation and number of plies in the joint section along with thelaminate in the panel section and the surrounding foam properties eachcan be used to optimize the shape and dimensions of the resultingcomposite structure to achieve a desired thermal characteristic,mechanical characteristic, weight or cost, or any combination of these.

An example of the industrial applicability of the invention is the caseof a fork lift operating inside the box of a refrigerated trailer. Forklift operators often use the wall as a guide to make sure the load is asclose to a side wall as possible. The result is that the forklift wheel,and, at times, the cargo, impact the wall and the slide along the wallof the trailer. Conventional shear ties with thin skinned laminates tendto have shear tie failure and or laminate skin failure at or near theshear tie in such situations. The large increase in transverse stiffnessoccurs on the wall panel suddenly as the deflection decreases nears therigid shear tie, imposing high stress concentration on the shear tie andlocally on the skin. This is a drawback of the prior art. In contrastthe nested C joint of the invention acts as an internal spring in thewall, transferring the load of the impact along the arcuate surfaces ofthe nested joints between panels, allowing the wall skin to deflect witha more gradual transition and flexible shear tie that preventsstructural failure or other damage to the wall and shear tie.

The mechanical and thermal properties of the nested C joint of theinvention may be tailored as desired for a specific application byselecting the fabric fibers, plies and orientations. In the same exampleof a refrigerated trailer, a fabric fiber orientation of +45-45 E-Glassfabric would likely be the preferred embodiment from a cost andperformance perspective. Additional fibers in the 90° orientation can beadded and or additional plies can be added to provide additionalresistance and load bearing.

The selection of fabric/resin laminate and supporting material, such asfoam, have a large impact on the overall wall performance. Higherdensity foams will provide more resistance and support thinner wallskins; however, they will tend to add weight and degrade thermalperformance. Foam densities in the 2.2-2.4 pounds per cubic feet rangehave been found to be the optimal for low cost polyurethane foams. Someof these low density polyurethane foams provide excellent insulationcharacteristics, are lightweight and can withstand large deformationswithout failures.

C joint spacing between panels, which may be determined by panel width,is another parameter that can be used to optimize properties. Increasingthe number of C joints makes each panel more resistant to flexural loadsand in-plane loads. Also distance between C joints does not need to beeven, i.e., a resulting planar structure may comprise panels ofdiffering widths. For example, in a refrigerated trailer, a highernumber of C joints may be used at the rear end and front ends of thetrailer box, where expected loads may be higher. Thus, a larger numberof C joints toward the rear of the trailer box would help mitigateglobal loading as a fork lift enters and exits the trailer. In the frontend of the trailer, a larger number of C joints, i.e. more frequentspacing between panels, assists in mitigating shock loads as the trailercoupler impacts the tractor, or when the tractor decouples allowing thetrailer to drop on the front support legs. In the same manner as above,in such applications the particular shape and laminate schedule of eachjoint can be optimized as needed, depending upon expected loadconditions.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated into and form a partof the specification, illustrate one or more embodiments of the presentinvention and, together with the description, serve to explain theprinciples of the invention. The drawings are only for the purpose ofillustrating the preferred embodiments of the invention and are not tobe construed as limiting the invention. In the drawings:

FIG. 1a depicts panels of the invention comprising the C joint of theinvention, showing the panels coming together to form an exemplaryplanar structure.

FIG. 1b depicts a cross-section of an embodiment of the C joint of theinvention, showing in detail an embodiment of an arcuate concave surfacedisposed on a first edge of a first panel, an embodiment of an arcuateconvex surface disposed on a second edge of the second panel, depictingfeatures of an embodiment of the nesting of the C joint of the inventionand further showing the fabric layers.

FIG. 2 depicts a cross-section of an embodiment of a panel of theinvention, showing the arcuate concave surface disposed on a first edgeof a panel and an arcuate convex surface disposed on a second edge of apanel of the invention and further showing the fabric layer of thestructural panel.

FIG. 3a depicts a cross sectional view of two foam panels of theinvention fitted together, depicting the C joint of the invention incross-section and providing further details of the C joint of theinvention into breakout detail views, in which an arcuate convex surfaceof an edge of a first panel is received by an arcuate concave surface ofan edge of a second panel, forming a nested joint between thecomplementary concave and convex arcuate surfaces on the first edge ofthe first panel of the invention and a second edge of the second panelof the invention; also shown is the advantage of the present inventionin reducing or eliminating print through depressions.

FIG. 3b depicts a cross sectional view of two panels of an alternateembodiment of the invention fitted together, depicting the C joint ofthe invention in cross-section and providing further details of the Cjoint of the invention into breakout detail views, in which an arcuateconvex surface of an edge of a first structural composite panel isjoined to an arcuate concave surface of an edge of a second structuralcomposite panel, and wherein convex surface step surfaces are joined toconcave surface step surfaces, forming a nested joint between thecomplimentary concave and convex arcuate surfaces on the first edge of afirst panel of the invention and a second edge of a second panel of theinvention.

FIG. 4 depicts a cross section view of a butt joint of the prior artused in joining panels, and further depicting a disadvantage of theprior art in which print through depressions are formed by shrinkage ofthe resin during curing.

FIG. 5a depicts a perspective view of an embodiment of the planarstructure of the invention in which a series of panels have beenassembled together utilizing the nested C joint of the invention,forming a contiguous planar structure which may be utilized, forexample, in the fabrication of thermally insulating containers, floorpanels, wall, roofs or other structures.

FIG. 5b depicts a cross-sectional view of an embodiment of the inventioncomprising a plurality of an embodiment of panels of the invention,showing a surrounding frame and structural panels in cross-section andfurther depicting the bonding surfaces that may be utilized to applychemical bonding in order to attach the structural panels of theinvention to the surrounding frame.

FIG. 6 depicts a perspective view of an embodiment of the invention inwhich a plurality of planar structures of the invention have beenassembled together utilizing the nesting C joint of the invention,forming a multi-sided sided structure forming an enclosure which may beutilized, for example, in the fabrication of thermally insulatedcontainers or other structures for use in numerous applications.

FIG. 7a depicts a schematic cross sectional view of a C joint of thepresent invention for purposes of comparison to the butt joint of theprior art, and describing the advantages of the present invention inproviding increased resistance to applied loads, increased reliabilityand ability of the C joint of the present invention to return to itsoriginal shape after an impact, and to depict thermally superiorproperties of the C joint of the present invention.

FIG. 7b depicts a schematic cross sectional view butt joint of the priorart for the purposes of demonstrating the inferior load bearingperformance of prior art.

FIG. 8 depicts a cross section view of an embodiment of a panel of thepresent invention.

FIGS. 9a and 9b depict flow charts describing methods of manufacture ofplanar structures of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The following documentation provides a detailed description of theinvention, and the accompanying figures depict exemplary embodiments ofthe invention.

It is an object of the system and method of the invention to provide animproved C joint for joining panels together, said C joint providingsuperior thermal performance by reducing the overall thermalconductivity from one planar surface of the assembled planar structureof the invention to an opposing planar surface; and providing superiorstructural performance by providing increased load bearing ability,durability and ability for the assembled panel to return to its originalshape after being impacted by a force, due to the novel geometry of theC joint.

It is a further object of the invention to provide a panel configured tobe used in the assembly of a planar structure comprising theadvantageous C joint of the invention.

It is a further object of the invention to provide a planar structurecomprised of panels that are assembled together using the nesting Cjoint of the invention. Such planar structures may be used, for example,as wall structures. The panels may comprise foam overlaid with fabricthat is saturated with resin that is subsequently cured. In anembodiment, the assembled planar structure is captured within a framethat may have a U-shaped cross section, and into which surfaces of theassembled wall panels may be inserted and chemically bonded.

It is further an object of the invention to provide a manufacturingmethod for producing the panels of the invention comprising the novelnested C joint of the invention.

It is a further object of the invention to describe and claim anassembled multisided structure comprising foam panels of the inventionwhich further comprise C joints of the invention and being assembledtogether using the nested C joints of the invention, substructure beingusable, for example, in thermally insulated intermodal shippingcontainers such as may be used in refrigerated shipping applicationssuch as over the road trucking, rail, shipboard transportation and thelike.

As used herein, “un-wetted” includes any composite structure or fabricthat has not been impregnated or coated with resin. “Wetted” means afabric has been impregnated or coated with resin. “Wet-out” means theprocess for applying, by impregnating, coating or likewise, a resin to afabric. In a fully wetted, or fully impregnated, fabric all or nearlyall of the fiber filaments are thoroughly saturated with the resin orresin mixture. “Wetting” means to apply resin to a fabric such that itthe fabric is fully wetted.

As used herein, “composite structure” includes a structure thatcomprises fabric intended to be impregnated, i.e. wetted, with resin,typically but not necessarily surrounding a supporting material, whichmay be but is not necessarily, foam.

As used herein “resin” includes any matrix or other material that isused to coat the fiber layers of a fiber-reinforced composite structureor preform. Resins may be natural or synthetic. Such resins include butare not limited to polymers (orthophthalic, isophthalic or otherwise),polyester resins, vinyl ester resins, epoxy resins, phenolic and anyother resin known in the art of composite structure manufacture. As usedherein, “resins” also includes any resign that is cured or polymerizedby application of light (regardless of wavelength), heat, electron beamcure that may utilize, for example, high energy electrons or X rays asionizing radiation, or any other type of cure. Light cure, as usedherein, also means “light-activated”, and includes all light curableresins including but not limited to one-part translucent polymers thatcure when exposed to a specific light spectrum. When the word “light” isused herein, it refers to light energy of an optical spectrum that ismatched to the light curable resin it is being used to cure. “Cure ondemand” resins mean any resin that does not self-cure: typically cure ondemand resins are cured by application of some external energy such asheat, light, ionizing radiation or any other energy source.

As used herein, “co-cure” or “co-cured” means resins that are co-curedwith, for example, gel coat, as described in U.S. Pat. No. 9,371,468,meaning, generally, that the reactions involved in producing a urethanepolymer (i.e., reaction of a polyisocyanate or NCO-terminated prepolymerwith polyols and hydroxy or amine-functional extenders) take placeessentially concurrently with reactions involved in converting vinylester epoxy, or unsaturated polyester reactants to cured products.Unsaturated polyester and vinyl ester resins generally react withstyrene and free-radical initiators to produce a cured thermosetpolyester or vinyl ester. Epoxy resins generally react with “hardeners”or curing agents to produce a cured epoxy component. The co-curedproduct comprising the urethane and polyester, epoxy, or vinyl estercomponents is distinguishable from an interpenetrating network (IPN)because there can be some reactions involving chains of each network.The meaning of “co-cure” includes all the teachings of U.S. Pat. No.9,371,468.

As used herein, “Fabric” includes any fibrous material known in the artof composite structure manufacture, either matt, woven, non-woven,chopped or otherwise, and may comprise fiberglass, carbon fiber, glassfibers, cellulose, polymers, for instance aramid, pararamid and thelike. Fabric may be backed or unbacked.

As used herein, “Fabric layer” includes a single or plurality of fabriclayers, of any type of fabric in any combination. For instance, “fabriclayer” may mean one layer of woven fabric, or may mean a layer of wovenfabric in conjunction with a layer of non-woven fabric. The system andmethod of the invention applies to any selection of fabric materials andthe number of layers as chosen by the user. Fabric layers need not becontinuous, in other words, fabric layers may be pieced together usingseparate pieces of fabric to comprise a completed layer.

As used herein, “Foam” includes any foam material used in the art ofcomposite structure manufacture, and includes, for example and not byway of limitation, polyurethane foam such as a self-expandingself-curing foam. Typically, for example, such a self-rising,self-curing foam is a urethane foam commercially available from BASF,MOBAY, or PPG, and is typically an MDI-based rigid polyurethane foam(methylene-diphenyl-methane diisocyanate or methylene diphenyldiisocyanate) using hydrogenated chlorofluorocarbons (HCFe), waterand/or CO2 as a blowing agent.

As used herein, “hybrid resin” includes any blend of resins, includingbut not limited to polyesters, vinyl esters, polyurethanes or epoxies,in any combination or ratios. The blend of these materials may betailored to achieve an optimal set of properties for a givenapplication.

As used herein, “planar” includes flat planar surfaces and curved planarsurfaces.

As used herein, “preform” means a structure comprising a supportingmaterial at least partially covered with a fabric that has been formedto a desired shape.

As used herein, “supporting material” means a material that supportslaminated structures comprising fabric impregnated with resin that issubsequently cured. Foam is a non-limiting example of a supportingmaterial.

“Joint” and “C joint” are used interchangeably.

The system and method of the invention includes within its scope alltypes of resins, fabrics, supporting materials, and combinationsthereof, and in fact that this is a distinct advantage of the presentinvention over the prior art.

The C Joint of the Invention

Referring now to FIG. 1a , panels 002 of the invention comprising the Cjoint 001 of the invention, showing the panels coming together to forman exemplary planar structure are depicted.

Referring now to FIG. 1b , the details of a typical C joint of theinvention 001 are shown. a cross-section of an embodiment of panels ofthe invention, showing in detail an embodiment of an arcuate concavesurface 101 disposed on a first edge of a first panel 002 a, anembodiment of an arcuate convex surface 102 disposed on a second edge ofa second panel 002 b, showing features of an embodiment of the C jointof the invention are depicted. Two panels of the invention 002 a and 002b may be assembled together using the C joint of the invention asdepicted in FIG. 1b . Each of the panels 002 a and 002 b may comprise anedge having complementary nesting arcuate surfaces 101 and 102 so thatthe panels 002 a and 002 b may be assembled together forming a nestedjoint between them. Arcuate surfaces 101 and 102 may be any arcuateshape desired. In a specific, non-limiting embodiment, arcuate surfaces101 and 102 may be defined by a radius R1. When the panels are broughttogether by motivating them in the direction of arrow A, thecomplementary arcuate surfaces 101 and 102 of panels 002 a and 002 bnest together to form a completed C joint of the invention as is furtherdepicted in FIG. 3A. Panel 002 a may further comprise a first planarsurface 103 a and a second planar surface 105 a, and panel 002 b maycomprise a third planar surface 103 a and a fourth planar surface 105 b.Thus, when two panels of the invention 002 a and 002 b are motivatedtogether to form a nested C joint, a planar structure, which may beused, for example, as a wall structure, comprising a contiguous fifthplanar surface 104 and sixth planar surface 106 is formed. Panels of theinvention 002 may comprise any supporting material 110 known in the art,such as for example foam. Furthermore, in an alternate embodiment,panels of invention 002 may comprise supporting material 110 that hasbeen covered with a fabric 111 which is saturated with resin which isthen cured by any curing means known in the art. In the case wherepanels of the invention 002 comprise foam material that has been coveredwith a fabric 111 saturated with resin, injection or infusion molding,or the manufacturing technique known as vacuum bagging, may be employedto wet and cure the resin saturating the fabric of panels 002 as isfurther explained below.

Still referring to FIG. 1b , radius R1 and radius R2 are selected suchthat when arcuate concave surface 101 and arcuate convex surface 102 arebrought together, they form a completed nested joint with substantiallyconstant contact between complimentary surfaces 101 and 102. In thespecific non-limiting case in which arcuate concave surface 101 andarcuate convex surface 102 are defined as a portion of an arc of acircle, radius R1 and radius R2 define the radius of the circle andarcuate concave surface 101 and arcuate convex surface 102 in thisembodiment are therefore defined as forming a portion of a circle whenviewed in cross-section as shown in FIG. 1b . However, it is notnecessary that arcuate concave surface 101 and convex surface 102comprise a geometry that is a portion of an arc of a circle. Concavesurface 101 and convex surface 102 may be any arcuate or curvilinearsurface that are complementary and form substantially constant contactbetween services 101 and 102 when assembled together to form a nested Cjoint. Such shapes include compound arcuate surfaces. Thus, for example,arcuate concave surface 101 and convex surface 102 may be elliptical,compound, or any other complementary shapes. In the case in whicharcuate concave surface 101 and convex surface 102 are not defined aspart of an arc of a circle, radius R1 and radius R2 are not utilized asthe radius of a circle to define concave surface 101 and convex surface102.

Referring now to FIG. 2, a cross-section of an embodiment of a foampanel of the invention, showing in detail an arcuate concave surface 101disposed on a first edge of a panel 002 and an arcuate convex surface102 disposed on a second edge of the panel of the invention 002, isdepicted. Panels of the invention 002 may comprise edges havingcomplementary arcuate surfaces so that the panels 002 may be assembledtogether as further depicted in FIG. 3a and described elsewhere hereinto form a planar structure. A first edge of a panel 002 may comprise aconcave arcuate surface 101. A second edge of a panel 002 may comprise aconvex arcuate surface 102, creating a male joining section as depictedin the figure. Each panel 002 may further comprise a first planarsurface forming a side 103 and a second planar surface forming a side105. In an embodiment, panels of invention 002 may comprise supportingmaterial, such as foam, 110 that has been covered with a fabricsaturated with resin which has been cured by any curing means known inthe art.

Referring now to FIG. 3a , a cross sectional view of two foam panels 002a and 002 b of an embodiment of the invention are depicted nestedtogether, depicting the C joint 001 of the invention in cross-sectionand providing further details of the C joint of the invention intobreakout detail views B and C, in which an arcuate convex surface 102 ofa first edge of a first panel 002 b is joined to an arcuate concavesurface 101 of a first edge of a second panel 002 b, forming astructural nested joint between panels 002 a and 002 b, are depicted;also shown is the advantage of the present invention in reducing oreliminating print through depressions.

Still referring to FIG. 3a , two or more structural panels 002 of theinvention, which may be fabricated as herein described, may comprise asupporting material such as a foam 110 covered with fabric 111, formingstructural panels that are brought together as shown in the figure. Eachstructural panel 002 a and 002 b may comprise a first planar surface 103a and 103 b, respectively, and a second planar surface 105 a and 105 b,respectively separated by a thickness T. Thickness T may be selected tobe of a dimension that is appropriate to bear the anticipated structuralloads, provide a desired thermal resistance, or may be selected to be ofa dimension specifically adapted to a particular purpose identified by auser. When a plurality of structural panels of the invention 002 arebrought together and assembled using the nested C joint of the inventionas depicted in the figure to form a planar, the plurality of surfaces103 a, 103 b and so on may be substantially aligned so as to form aresulting fifth planar surface 104; likewise, the plurality of surfaces105 a, 105 b and so on may be substantially aligned so as to form aresulting sixth planar surface 106. The resulting planar surfaces 104and 106 of the panel assembly may be further overlaid by fabric layer107. The arcuate concave surfaces 101 and arcuate convex surfaces 102comprising edges of structural panels 002 nest together as hereinbeforedescribed.

Still referring to FIG. 3a , detail B depicts an expanded view of aportion of an embodiment of the C joint of the invention. A first panel002 a and second panel 002 b have been assembled together ashereinbefore described. Arcuate concave surface 101 and arcuate convexsurface 102 may be in substantial contact forming a nested C joint. Thepanels comprise supporting material 110 and are covered by fabric 111,with an overlaying fabric layer or layers 107. Likewise, detail Cdepicts an expanded view of a portion of the C joint of the invention onthe opposite side of the panel C-joint. A first panel 002 a and secondpanel 002 b have been assembled together as hereinbefore described.Arcuate concave surface 101 and arcuate convex surface 102 may be insubstantial contact forming a nested joint, and may be bonded togetherusing an epoxy or other chemical bonding agent is desired by the userfor particular application. The panels comprise supporting material 110and are covered by fabric 111, with an overlaying fabric layer or layers107.

Still referring to FIG. 3a , the joining of surfaces 101 and 102 betweentwo panels 002 a and 002 b using the C joint configuration of theinvention depicted in Details B and C may form a continuous nested Cjoint running the length of one edge of the joined panels. In thismanner, a plurality of panels may be joined together having nested Cjoints running the length of the panels between them, thereby forming aplanar structure having planar surfaces on either side. The resultingplanar structure may be a flat or curved planar structure. Such panelassemblies may be utilized in numerous and varied structural and otherapplications including but not limited to, for example and not by way oflimitation, wall assemblies suitable for constructing thermallyinsulated containers and the like.

Still referring to FIG. 3a detail views B and C, and also to FIG. 4, afurther advantage of the C-joint of the present invention isillustrated. It is a known feature in the art of structural compositefabrication that when composite panels are brought together using a buttjoint to form a prior art panel assembly 1000 such as depicted in FIG.4, a phenomenon known as “print through” depicted as feature 1004 inFIG. 4 may occur during the wetting and subsequent resin curingprocesses of the panel assembly. Print through 1004 manifests as adepression in the outer surface of a panel of the prior art, saiddepression 1004 running the length of butt joint 1003. Thus, when twobutt joint panels 1001 and 1002 of the prior art are brought togetherand overlaid with fabric 1005 then subsequently wetted with resin andcured, an unsightly print through 1004 depression occurs running thelength of butt joint 1003 due to resin shrinkage during curing process,and the fact that, at the point of contact between the butt joinedpanels, the butt joint supporting material does not uniformly supportthe resin as it is cured. This is a significant disadvantage of theprior art. In contrast, referring again to FIG. 3a detail views B and C,print through 120 in the present invention is significantly reduced oreliminated altogether in the finished multi-panel planar structure,i.e., dimension 121 is minimized or even brought to zero. This is due tothe fact that the arcuate services and their fabric overlay meantoperate to evenly distribute the forces resulting from the wetting andresin curing process due to the geometry of the C-joint, and the C jointforms a supporting surface under the fabric layers at 450, helping toprevent print through. This is another significant advantage of thepresent invention over prior art attempts to fabricate multi-panel wallstructures using structural composite materials as print through is ahighly undesirable feature in many applications, for cosmetic and otherreasons.

Referring now to FIG. 3b , an alternate embodiment of the C joint isdepicted in cross section. Two structural panels 002 a and 002 b of theinvention are shown fitted together, depicting the alternative C jointof the invention in cross-section and providing further details of the Cjoint of the invention into breakout detail views, in which an arcuateconvex surface of an edge of a first structural composite panel isjoined to an arcuate concave surface of an edge of a second structuralcomposite panel, and wherein convex surface step surfaces are joined toconcave surface step surfaces, forming a fitted joint between a firststructural composite panel 002 a of the invention and a secondstructural composite panel 002 b of the invention.

Still referring to FIG. 3a , two or more structural panels 002 of theinvention, which may be fabricated as herein described, may comprise asupporting material such as a foam 110 covered with fabric 111, formingstructural panels that are brought together as shown in the figure. Eachstructural panel 002 a and 002 b may comprise a first planar surface 103a and 103 b, respectively, and a second planar surface 105 a and 105 b,respectively separated by a thickness T. Thickness T may be selected tobe of a dimension that is appropriate to bear the anticipated structuralloads, provide a desired thermal resistance, or may be selected to be ofa dimension specifically adapted to a particular purpose identified by auser. When a plurality of structural panels of the invention 002 arebrought together and assembled using the nested C joint of the inventionas depicted in the figure to form a planar, the plurality of surfaces103 a, 103 b and so on may be substantially aligned so as to form aresulting fifth planar surface 104; likewise, the plurality of surfaces105 a, 105 b and so on may be substantially aligned so as to form aresulting sixth planar surface 106. The resulting planar surfaces 104and 106 of the panel assembly may be further overlaid by fabric layer107. The arcuate concave surfaces 101 and arcuate convex surfaces 102comprising edges of structural panels 002 a and 102 b nest together ashereinbefore described.

Still referring to FIG. 3b , detail D depicts an expanded view of aportion of the C joint of the invention is depicted. A first panel 002 aand second panel 00 b 2 have been assembled together as hereinbeforedescribed. Arcuate concave surface 101 and arcuate convex surface 102may be in substantial contact. The panels comprise a supporting materialfoam 110 and are covered by fabric 111, with an overlaying fabric 107.Convex surface step surface 132 is adapted to receive concave surfacesubsurface 133. Convex surface step surface 132 may be substantially incontact with concave surface 133. Step 130 formed by convex surface tosurface 132 and concave surface step surface 133 may be of dimension131. Likewise, detail E depicts an expanded view of a portion of the Cjoint of the invention on the opposite side of the panel joint isdepicted in detail D. A first panel 002 and second panel 002 have beenassembled together as hereinbefore described. Arcuate concave surface101 and arcuate convex surface 102 may be in substantial contact, andmay be bonded together using an epoxy or other chemical bonding agent isdesired by the user for particular application. The panels may be of anymaterial but, in a preferred embodiment, may comprise structural from110 are covered by fabric 111, with an overlaying fabric 107. Convexsurface step surface 132 is adapted to receive concave surfacesubsurface 133. Convex surface step surface 132 may be substantially incontact with concave surface 133 and these two surfaces may be bondedtogether using epoxy or other chemical bonding agents as may be desiredby the user. Step 130 formed by convex surface to surface 132 andconcave surface step surface 133 may be of dimension 131, which may beany dimension but may be, for example, a dimension equal to one later offabric saturated with resin.

Still referring to FIG. 3b , the joining of surfaces between two panels002 using the alternative C joint embodiment of the invention depictedin Details D and E, when brought together, may form a continuous nestedjoint running the length of one edge of the joint panels. In thismanner, a plurality of panels may be joined together having nestedjoints running the length of the panels between them, thereby forming aresulting planar structure having resulting planar surfaces on eitherside. Such panel assemblies may be utilized in numerous and variedstructural and other applications including but not limited to, forexample and not by way of limitation, wall assemblies suitable forconstructing thermally insulated containers and the like.

Referring now to FIG. 5a , a perspective view of an embodiment of theinvention in which a series of panels have been assembled togetherutilizing the C joint of the invention, forming a resulting planarstructure which may be utilized, for example, in the fabrication ofthermally insulating containers or other structures, is depicted. Theresulting planar structure may be curved or flat. For simplicity sake, aflat structure is depicted in FIG. 5a . A plurality, which may be anynumber, of panels 002 of the invention are joined together using nestedC joints 001 of the invention between them as hereinbefore described toform a planar structure having a first planar surface and a secondplanar surface and, in the non-limiting example in which the resultingplanar structure is a flat planar structure, forming a wall likeconfiguration. The plurality of panels 002 may be further overlaid byfabric layer or layers, and all the fabric panels and overlay fabric maybe wedded with resin and the resin subsequently cured at the same time.Thus, in this manner, a series of panels 002 are brought together toform a planar structure. The dimensions of the final structure may takeany dimensions as may be desired by the user for a particularapplication, likewise, the thickness of panels 002 may take anydimension as may be desired by a user for a particular application. Theplurality of panels 002 may be received by and bonded to a frame 115that may be any shape adapted to receive panels 002, but in anon-limiting example may be of U-shaped cross-section as is furtherdepicted in FIG. 5B. In this matter a planar structure may bemanufactured, and the resulting planar structure may be useful forassembly into numerous and varied structural applications such as, forexample and not by way of limitation, construction of shippingcontainers, especially thermally insulated structural shippingcontainers that may be used in intermodal shipping.

Still referring to FIG. 5a , an exemplary planar structure may befabricated using the following process. In a first step, a plurality ofpanels 002 are fabricated as described above. In a second step, frame115 is fabricated by any means known in the art. In a third step, thepanels may then be assembled into frame 115. In a fourth step, fabriclayer or layers 107 may be then be laid over or wrapped around un-wettedpanels 002. In a fifth step, the fabric layers may then be wetted withresin and the entire assembly may be vacuum bagged while the resincures, producing a finished planar structure that is bonded to frame115. Alternatively, panels 002 may be wetted with resin and cured priorto being assembled together. In this alternative method, panels 002 thathave been wetted with resin and cured are assembled together in thethird step, and the process continues with the fourth step of applyingfabric layer 107 laid over or over wrapping wetted and cured panels 002,and in the fifth step fabric layer 107 may be wetted with resin andcured while the wall assembly is vacuum bagged.

Referring now to FIG. 5b , a cross-section of the multi-panel wallassembly depicted in FIG. 5a is shown. A plurality of panels 002 havebeen brought together, as depicted in FIG. 5a , said panels being joinedby nested C joints of the invention. Thus, arcuate concave surfaces 101are in substantial contact with, arcuate convex surfaces 102. Panels 002are overlaid by fabric 107. The resulting planar structure is receivedby channels 115, and the edge of the wall assembly that is in contactwith the interior surfaces of channels 115 may comprise any joint suchas, for example, a butt joint as depicted in the figure. The interiorsurfaces of channels 115 may be bonded to the outer surfaces of theresulting planar structure in the areas designated as H by any chemicalbonding means known in the art such as, for example and not by way oflimitation, epoxy or resin. Alternatively, the resulting planarstructure may be bonded to frame 115 during wet-out and cure of theresin saturating the fabric layers. Frame 115 may comprise metal such asaluminum, steel or any other metal that has been joined together forminga frame such as that depicted in FIG. 5a . In an embodiment of theinvention, frame 115 may comprise joints that are joined by mitering,welding of the miter joints. The resulting weld joints may besubsequently ground so that an aesthetically pleasing frame is produced.Alternatively, frame 115 may comprise fiberglass that has been shaped ina U-section as depicted in the drawing, or in any other shape that isadapted to receive panels 002. In the exemplary embodiment of theinvention depicted in FIG. 5a the resulting planar structure issubstantially rectangular in outline; however, the geometric shape ofthe resulting planar structure is not to be limited to rectangularshapes that may be in a shape as desired by a user for a particularapplication. Thus all planar structure outlines are within the scope ofthe invention.

Referring now to FIG. 6, a perspective view of an embodiment of theinvention in which a plurality of panels have been assembled togetherutilizing the nested C joint of the invention, forming a four sidedstructure, such as an enclosure, which may be utilized, for example, inthe fabrication of thermally insulated containers for shipping, isdepicted. The embodiment of the invention depicted in FIG. 6 isexemplary; any number of possible configurations of the inventionutilizing resulting flat or cured planar structures are within the scopeof the invention. The four sided exemplary structure depicted in FIG. 6comprises a first side 201, a second side 202 a third side 203, and afourth side 204. Each side comprises multiple panels 002 of theinvention that have been brought together as hereinbefore described,forming substantially wall shaped structures as depicted in FIGS. 5A and5B. Panels 002 may comprise frames 115. Sides 201, 202, 203 and 204 areassembled together forming a substantially rectangular box shape asdepicted in the figure. Sides 201, 200, 203, and 204 may be joinedtogether at joints 200 using any means known in the art including butnot limited to threaded fasteners, rivets, chemical bonding, welding,and any other form of mechanical assembly known in the mechanical arts.In this manner, a container such as a thermally insulating shippingcontainer may be constructed that exhibits all the superior features ofthe novel elements of the invention, namely, superior thermalinsulation, lightweight, lower cost of manufacturing, resistance tostructural loads, resistance to corrosion, and other advantageousfeatures.

The advantage of a C-joint of the present invention over a butt joint ofthe prior art is further shown in FIGS. 7a and 7b . FIG. 7a depicts across section view of a panel of the invention subjected to a load F,depicting an exemplary deflection of the panel and the resultingtransfer of load along the C-joint without structural failure of thejoint or panel, demonstrating an advantage of the panel and C-joint ofthe invention. FIG. 7b depicts, for comparison purposes to the nested Cjoint of the invention, a cross section view of a prior art panelcomprised of a butt joint subjected to a load F, depicting an exemplarydeflection of the panel and the resulting failure of the prior art buttjoint. As depicted in FIG. 7a , a load F acting on a C-joint of theinvention may result in a deflection J′. When load F is applied to theC-joint the load is distributed around and along arcuate surfaces 101and 102 as shown by arrow G and thus some of the transverse loading isredirected longitudinally into the foam material, where it is absorbed.The nested arcuate surfaces covered with fabric, wetted with resin andcured, create a “spring” like structure within the C joint that is ableto flex in the direction of arrow I, thus acting to absorb applied loadswith failure. This is because, among other things, the 90° joint stressriser of the prior art butt joint is eliminated. The result is reducedshear forces in the nested C joint between the two joined panels, a moreresilient structure, and a higher loading capacity that the butt jointsof the prior art. This is a distinct advantage of the nested C-joint ofthe invention over a prior art butt joint as depicted in FIG. 7c , inwhich it is clearly seen that application of load F to the butt jointcausing deflection J″ results in separation of the panel edges L at thebutt joint 1003, which may cause a rupture of the fabric layer at K,resulting in structural failure of the prior art butt joint panel. Thusthe nested C joint of the present invention exhibits superior loadbearing qualities over the butt joints of the prior art. Still further,the same paths as described above and depicted in FIGS. 7A and 7B areapplicable to thermal conductivity of the nested C joint. Thus, thethermal path through the C-joint is longer than the thermal path througha butt joint due to the arcuate shape joining the panels of the presentinvention: the arcuate shape results in a longer thermal conduction pathand thus in increased thermal resistance from one side of the C joint tothe other side. This is in contrast to the butt joint depicted in FIG.7A which has a direct linear thermal path and is therefore lessthermally resistive than the C-joint of the present invention. It canthus be seen that the C-joint of the present invention provides superiorstructural loadbearing and thermal insulating properties of thestructures of the prior art.

Referring now to FIG. 8, a particular, non-limiting exemplary embodimentof the C-joint of the present invention is depicted. The particularembodiment of the C-joint of the invention comprises outer fabric layers107, which form first planar surface 103 and second planar surface 105.Fabric layers 111 cover structural material 110 as described herein.During fabrication, fabric layer 111 does not necessarily need to extendacross the entirety of supporting material 110. Fabric layer 111 mayterminate at point M underneath fabric layer 107. During the fabricationprocess, a “tail” of fabric extending beyond the terminus of supportingmaterial 110 may occur. This tail may be trimmed to a desired dimensiondesignated as TRIM in the figure such that the concave arcuate surface101 is adapted to receive the convex arcuate surface 102 of an adjoiningpanel without interference.

Any embodiment of the invention may comprise structural plates, bracketsor other structures for bearing loads, attachment to other structures,or the like. These structures may be embedded in panels or planarstructures of the invention by placing or bonding them in place at adesired location prior to or after wetting out the fabric and curing theresin.

The dimensions of the invention may take on any value as desired by auser, and thus the C-joint radius, panel thickness, length of overlap offabric layers, panel width separation between structural plates and allother dimensions may be of any measure desired.

In the embodiments of the invention in which panels 002 comprise foammaterial that has been covered with a fabric saturated with resin, thefabric layers may comprise a single layer of fabric or a plurality oflayers comprising either woven fabric, non-woven fabric, or acombination of woven and non-woven fabric.

The fabric layers as set forth herein may comprise one or moreindividual fabric layers, and each layer need not be continuous. In thecase where multiple layers of fabrics are utilized, it is not necessarythat each type of fabric comprising a fabric layer be of the same typeor weight. In a preferred embodiment of the invention, fabric layer 111may be two ounce per square foot fabric. Further, in a preferredembodiment of the invention, overlaying fabric layer 107 may be twelve,twenty-four or thirty-six ounce per square yard fabric oriented at 45°to the sides of structural panel 002, the structural panel beingsubstantially rectangular in shape. However, the type of fabric utilizedin fabric layers 111 and 107 may be any type of fabric, may be of anyorientation, may be backed or unbacked, and may be of any weight as maybe selected by a user for particular structural application. Further, ina preferred embodiment, panels of the invention 002 may be placed ontwelve to twenty-four inch centers when utilized to construct a wallstructure as is depicted, for example, in FIG. 5a . It is to beunderstood however that wall panels 002 of the invention may be of suchdimension that they may be placed on any desired center spacing, thatthey are not necessarily of rectangular shape and that the scope of theinvention is not limited to the specific configuration of panel asdepicted in the figures as the embodiments depicted in the figures areexemplary only. Likewise, for a preferred embodiment of the invention,thickness T may be in the range of one to four inches; but thickness Tmay take any dimension desired by a user for a particular application.

Method of Manufacturing

Panels and planar structures comprising the C joint of the invention maybe fabricated by any manufacturing technique, including those identifiedherein, such as open molding, close molding injection in which resin ispumped into a closed mold under pressure for wetting the fabric, openhand lay-up, closed mold infusion in which the pressure is reduced inthe mold pulling resin into the mold for wetting the fabric, resintransfer molding, vacuum assisted resin transfer molding, cold press,wet vacuum bagging and variations of these processes.

Referring now to FIG. 9a , the steps, generally, of manufacturing aplanar structure of the invention include providing a supportingmaterial and fabric 600; creating a plurality of panels 002, or 002 aand 002 b, as depicted in FIGS. 1a, 1b , 2, 3 a and 3 b, each panelcomprising the C joints of the invention wherein each panel of saidplurality of panels comprises a first planar surface, a second planarsurface, a first edge, and a second edge, each of said first planarsurface, second planar surface, said first edge and said second edgecovered with at least one layer of fabric covering a supporting materialsuch as foam, 601. In a next step 602 the plurality of panels areassembled together using any of the techniques described here, or as maybe known in the art, forming a resulting planar structure comprised ofadjoining panels joined together at a nested joint in which the convexarcuate surface of one panel of said plurality of panels is nested intothe concave arcuate surface of an adjoining panel of said plurality ofpanels, said resulting planar structure having a resulting first planarsurface and a resulting second planar surface. In a next step 603, eachof the fabric layers are wetted with a resin. In a next step 604 theresin is cured, forming a resulting planar structure 605. The panels 002may be created as a preform. Referring to FIG. 9b , the same steps ofthe general method of manufacture are depicted as described aboveregarding FIG. 9a , except the steps assembling 602 and wetting 603 arereversed. Thus the fabric layers may be wetted prior to, or after,placing the panels together. After the panels are placed together andthe fabric is wetted with resin, the resin is cured, forming a completedplanar structure comprised of one or more panels. Various techniques forcarrying out these steps of manufacture are described herein. The methodsteps of FIGS. 9a and 9b are exemplary, and not limiting.

Preforms for panels of the invention may be fabricated using the methodfor manufacturing structural pre-forms taught and described in U.S. Pat.No. 6,543,469, SYSTEM FOR CONTINUOUSLY MANUFACTURING A COMPOSITE PREFORMto Lewit et al., (“the '469 patent”), or a pre-formed structuralcomposite structure formed by the method disclosed and taught in U.S.Pat. No. 5,897,818, METHOD FOR CONTINUOUSLY MANUFACTURING A COMPOSITEPREFORM to Lewit et al., (“the '818 patent”). Preforms may bemanufactured using these methods in a continuous feed that may operatespeeds of 16 feet per minute (fpm or ft/min) or greater, both of whichare hereby incorporated by reference in their entirety.

Preforms for panels of the invention 002 may also be fabricated using amold. A mold comprising a desired shape of the panel may be provided,and the interior surfaces of the mold may be covered with a desiredfabric or plurality of fabric materials. Expanding foam may then beapplied into the mold such that it penetrates the interstices of thefabric; the mold may be closed while the foam expands and/or cures; andthen the structural preform may be removed from the mold as taught inU.S. Pat. No. 6,013,213 to Lewit et al. METHOD FOR MAKING DEFORMABLECOMPOSITE STRUCTURES AND ASSEMBLING COMPOSITE ARTICLE (“the '213patent”), and also in U.S. Pat. No. 5,429,066 COMPOSITE STRUCTURES ANDMETHOD OF MAKING COMPOSITE STRUCTURES (the '066 patent). Alternatively,the mold may be closed prior to injecting the foam, and the foam maythen be injected into the interior of the mold though an opening in themold wall or a mechanical fitting capable of allowing the passage offoam into the mold, again as taught in the '213 patent. After theexpanding foam has cured the fabric may be saturated with resin andcured.

In still a further alternate embodiment of manufacturing performs forpanels of the invention 002, a panel 002 may be created by arranging afabric or layers of fabric in a configuration constrained againstoutward movement and defining a cavity between opposing surfaces of thefabric or fabric layers; dispensing a predetermined amount of anexpanding, self-curable, uncured foam into the cavity, the foamexpanding and curing in the cavity at a molding pressure determined bythe predetermined amount of the foam and thereby attaching itself to thefabric layer to form the composite structure, the molding pressurecausing the expanding foam to substantially fill only interstices of aninner portion of the fabric layer, without substantially penetrating anouter portion of the fabric layer; and, freeing the cured compositestructure from the constraint of the arranging step, the outer portionof the fabric layer of the composite structure being thereaftersubstantially completely saturable with a curable material forlamination to another structure in a subsequent processing step. Thisalternate method for creating a structural preform is taught in U.S.Pat. No. 5,908,591 METHOD FOR MAKING COMPOSITE STRUCTURES to Lewit etal.

A method of manufacturing panels of the invention 002 may comprise theabove steps for creating a panel 002 covered with a fabric or fabrics,which may then be followed by followed by a wet-out step, in which resinis applied to the structural preform in order to saturate the fabricwith resin. In this step, resin may be applied to the fabric coveringthe composite preform by any means known in the art including but notlimited to spraying, brushing, by applying resin through channels andorifices in a mechanical wetting die such that the resin is applied tothe fabric covering the structural preform, or by another means knownfor applying resin to a structural preform.

After a panel of the invention 002 is formed, and saturated with resin,and assembled with other panels by nested C joints to form a planarstructure, a cure step may follow, in which the applied resin is cured,or at least partially cured. In this cure step, the resin may be curedby application of heat, such as is the case, for example, when athermoset resin is utilized, by ultraviolet or other frequency of lightsuch as is the case, for example, when light-curable resin is utilized,by ionizing radiation such as electron beam radiation, or by any othermeans known in the art for the curing of resin.

The technique known as vacuum bagging may be utilized to fully saturateand cure the resin saturating the fabric of a plurality of panels thathave been assembled to form a planar structure. In this embodiment ofthe method of the invention, a plurality of panels are brought together,the concave surfaces and convex surfaces forming a nested C joint, orplurality of nested C joints, between adjoining panels as taught herein.Preforms for panels 002 may be wetted out prior to assembly by handspraying or by any of the methods for wetting a structural compositefabric-covered foam preform as taught in United States printed patentpublication number US2014-0262011 A1, titled STRUCTURAL COMPOSITEPREFORM WET-OUT AND CURING SYSTEM AND METHOD, published by the USPTO onSep. 18, 2014. Alternatively, preforms for panels 002 may be wetted outby spraying or otherwise applying resin to the fabric layers of thepanels by any means known in the art. After wetting, a vacuum bag may beplaced over the wetted assembled panels, and pressure is then reducedinside the vacuum bag using a vacuum pump connected to the vacuum bag,removing air form inside the bag and forcing resin to fully saturate thefabric covering the panels. The resin is allowed to cure, resulting in acompleted planar structure of the invention.

The techniques known as injection or infusion molding may be also beutilized to fully saturate and cure the resin saturating the fabric of aplurality of panels that have been assembled to form a planar structure.In this embodiment of the method of the invention, a plurality of panelsare brought together, the concave surfaces and convex surfaces forming anested C joint, or plurality of nested C joints, between adjoiningpanels as taught herein. Preforms for panels 002 may be wetted out priorto assembly by hand spraying or by any of the methods for wetting astructural composite fabric-covered foam preform as taught in UnitedStates printed patent publication number US2014-0262011 A1, titledSTRUCTURAL COMPOSITE PREFORM WET-OUT AND CURING SYSTEM AND METHOD,published by the USPTO on Sep. 18, 2014. Panel preforms, either wetted,partially wetted, or unwetted, may be placed in a closed mold, and resinmay then be injected into the mold under pressure for wetting the fabriclayers, in an injection molding step. Likewise, panel preforms, eitherwetted, partially wetted, or unwetted, may be placed in a closed mold,and air may be evacuated from the mold using a vacuum pump while resinis introduced into the mold. The reduced pressure inside the mold pullsthe resin into the fabric, wetting the fabric. In both infusion andinjection molding the resin is cured after the fabric is fully wetted,resulting in a completed planar structure of the invention.

Planar structures comprising the C-joint of the invention may also befabricated by any of the processes described in U.S. Pat. No. 9,371,468,titled CO-CURED GEL COATS, ELASTOMERIC COATINGS, STRUCTURAL LAYERS, ANDIN-MOLD PROCESSES FOR THEIR USE, which issued from the USPTO on Jun. 21,2016. For example, in the case in which the multi-panel planarstructures of the invention are manufactured using the vacuum bagging,injection-molding, or infusing molding processes, gel coat and resin maybe simultaneously cured using the methods taught in the '468 patent,resulting in reduced time for manufacture of a gel-coated, finishedmulti-panel planar structures.

While exemplary embodiments of the present invention have been describedin the written description and depicted in the figures of the drawings,the present invention is not to be limited by the examples shown and isto be construed to comprise all equivalent embodiments. Specifically,for simplicity and brevity sake, rectangular panel shapes have beendepicted in the figures of the drawings, but it is to be understood thatthe embodiments of the figures are exemplary only and that the panels ofthe invention may take any shape as desired, which may include arcuatesurfaces, exterior shapes that are not wall like in nature and are notconstrained before sided rectangular shapes as depicted in the figures,or in the other variation in shape or size, as such other shapes andconfigurations are construed to be within the scope of the presentinvention. The invention is not limited by the proportion betweenelements depicted in the drawings.

INDUSTRIAL APPLICABILITY

The panel joining system and method of the invention described andclaimed comprises a structurally robust, mass producible, structuralcomposite preform panel that further comprises features that enableaccurate assembly, and of which a plurality may be assembled together toform a planar or other formed structural surface such as a wall, whichmay then be used to constructive a thermally insulative, structurallyrobust composite structure. The panels of the invention may be massproduced so that economies of scale are realized. The compositestructure of the invention is also corrosion resistant and light weight.

Panels and panel assemblies comprising the panel joining system of theinvention or produced by the method of the invention provide dramaticimprovements in weight, durability, and thermal insulation over panelsof the prior art that are commonly used in applications such as tractortrailer bodies. Such improvements allow for stronger, lighter weightfreight containers, resulting in reduced fuel consumption, reducedcarbon footprint for users of the invention, and lower fuel andtransportation costs. Panels and panel assemblies comprising the paneljoining system of the invention or produced by the method of theinvention have also demonstrated an ability to absorb greater appliedbefore experiencing structural failure than panels fabricated bymaterials and methods of the prior art, meaning that they have longerlifetimes and thus result in lower maintenance and replacement costs.

What is claimed is:
 1. A joint for attaching adjacent panels,comprising: a first preform panel having a first edge, a first planarsurface, and a second planar surface, said first edge comprising aconcave arcuate surface; and a second preform panel having a secondedge, a third planar surface, and a fourth planar surface, said secondedge comprising a convex arcuate surface; wherein said concave arcuatesurface and said convex arcuate surface are complementary; wherein saidconcave arcuate surface is adapted to receive said convex arcuatesurface when said first edge of said first preform panel and said secondedge of said second preform panel are brought together, said concavearcuate surface and said convex arcuate surface together forming anested joint, and wherein said first planar surface and said thirdplanar surface together form a resulting fifth planar surface, and saidsecond planar surface and said fourth planar surface together form aresulting sixth planar surface; and wherein said first preform panel andsaid second preform panel each comprise foam covered by a first fabriclayer comprising at least one layer of fabric, such that said firstedge, said first planar surface, and second planar surface of said firstpanel, and said second edge, said third planar surface, and said fourthplanar surface of said second panel are each at least partially coveredby said first fabric layer; wherein the nested joint comprises at leasttwo layers of fabric between the convex arcuate surface and the concavearcuate surface, at least one layer of said at least two layers formedof said first layer of fabric seamlessly covering said concave surfaceof said first preform, and at least one layer of said at least twolayers formed of said first layer of fabric seamlessly covering saidconvex surface of said second preform; and wherein said first fabriclayer is wetted with a resin that is subsequently cured; such that thefabric layers within the nested joint, after they are wetted with aresin that is subsequently cured, form a spring-like structure withinthe nested joint that is able to flex in a direction transverse to thenested joint when a load is applied to said fifth surface or said sixthsurface at the nested joint, the load being distributed along thearcuate surfaces, where a portion of the load is transferred to adirection transverse to the nested joint.
 2. The joint of claim 1,wherein said concave arcuate surface and said convex arcuate surface aredefined as a portion of a circular arc defined by a radius.
 3. The jointof claim 1, wherein said resulting fifth planar surface and said sixthplanar surface are each overlaid by a second fabric layer comprising atleast one layer of fabric that is wetted with a resin that issubsequently cured.
 4. The joint of claim 2, wherein said resultingfifth planar surface and said sixth planar surface are each overlaid bya second fabric layer comprising at least one layer of fabric that iswetted with a resin that is subsequently cured.
 5. The joint of claim 1,wherein said foam is further defined to be polyurethane foam.
 6. Thejoint of claim 1, wherein said first fabric layer comprises fibersselected from the group consisting of fiberglass, carbon fiber, andpara-aramid synthetic fiber, and wherein said resin is selected from thegroup consisting of polymer resin, polyester resin, vinyl ester resin,polyurethane resin, epoxy, hybrid resin, and co-cured resin.
 7. Thejoint of claim 3, wherein said first fabric layer and said second fabriclayer are each individually comprised of fibers selected from the groupconsisting of fiberglass, carbon fiber, and para-aramid synthetic fiber,and wherein said resin is selected from the group consisting of polymerresin, polyester resin, vinyl ester resin, polyurethane resin, epoxy,hybrid resin, and co-cured resin.
 8. A planar structure, comprising: aplurality of adjoining preform panels, wherein each preform panelcomprises a first planar surface, a second planar surface, a first edge,and a second edge, each of said first planar surface, second planarsurface, said first edge and said second edge covered by a first fabriclayer comprising at least one layer of fabric; wherein said first edgeof each of said plurality of preform panels is defined as comprising aconcave arcuate surface; and wherein said second edge of each of saidplurality of preform panels is defined as comprising a convex arcuatesurface; and wherein said concave arcuate surfaces are complementary tosaid convex arcuate surfaces and wherein said concave arcuate surface isadapted to receive said convex arcuate surface when said first edge ofsaid first preform panel and said second edge of said second preformpanel are brought together, forming a nested joint between adjoiningpreform panels; each panel of said plurality of panels attached to anadjoining panel by a nested joint; said plurality of preform panelshaving a resulting third planar surface formed by the first planarsurfaces of each of the plurality of preform panels, and having aresulting fourth planar surface formed by the second planar surfaces ofeach of the plurality of preform panels; wherein the nested jointcomprises at least two layers of fabric between the convex arcuatesurface and the concave arcuate surface, at least one layer of said atleast two layers formed of said first layer of fabric seamlesslycovering said concave surface of said first preform, and at least onelayer of said at least two layers formed of said first layer of fabricseamlessly covering said convex surface of said second preform; whereinsaid first fabric layer is wetted with a resin that is subsequentlycured; such that the fabric layers within the nested joint, after theyare wetted with a resin that is subsequently cured, form a spring-likestructure within the nested joint that is able to flex in a directiontransverse to the nested joint when a load is applied to said fifthsurface or said sixth surface at the nested joint, the load beingdistributed along the arcuate surfaces, where a portion of the load istransferred to a direction transverse to the nested joint.
 9. The planarstructure of claim 8, wherein said concave arcuate surfaces and saidconvex arcuate surfaces are further defined as a portion of an arcdefined by a radius.
 10. The planar structure of claim 8, wherein saidresulting third planar surface and said fourth planar surface are eachoverlaid with a second fabric layer comprising at least one layer offabric that is wetted with a resin that is subsequently cured.
 11. Theplanar structure of claim 8, wherein said foam is further defined to bepolyurethane foam.
 12. The planar structure of claim 8, wherein saidfirst fabric layer is comprised of fibers selected from the groupconsisting of fiberglass, carbon fiber, and para-aramid synthetic fiber,and wherein said resin is selected from the group consisting of polymerresin, polyester resin, vinyl ester resin, polyurethane resin, epoxy,hybrid resin, and co-cured resin.
 13. A method of fabricating a planarstructure, comprising: providing a plurality of preform panels, eachpreform panel comprising foam covered by a first fabric layer comprisinga least one layer of fabric, wherein each preform panel of saidplurality of panels comprises a first planar surface, a second planarsurface, a first edge, and a second edge, each of said first planarsurface, second planar surface, said first edge and said second edgecovered by said first fabric layer; wherein said first edge of eachpreform panel of said plurality of preform panels is defined ascomprising a concave arcuate surface in cross section; and wherein saidsecond edge of each preform panel of said plurality of preform panels isdefined as comprising a convex arcuate surface in cross section;assembling plurality of preform panels together forming a resultingplanar structure comprised of adjoining preform panels joined togetherat a nested joint in which the convex arcuate surface of one preformpanel of said plurality of preform panels is nested into the concavearcuate surface of an adjoining preform panel of said plurality ofpreform panels, said resulting planar structure having a resulting firstplanar surface and a resulting second planar surface, wherein the nestedjoint comprises at least two layers of fabric between the convex arcuatesurface and the concave arcuate surface, at least one layer of said atleast two layers formed of said first layer of fabric seamlesslycovering said concave surface of said first preform, and at least onelayer of said at least two layers formed of said first layer of fabricseamlessly covering said convex surface of said second preform; wettingsaid first fabric layer with a resin; and curing said resin; such thatthe fabric layers within the nested joint, after they are wetted with aresin that is subsequently cured, form a spring-like structure withinthe nested joint that is able to flex in a direction transverse to thenested joint when a load is applied to said fifth surface or said sixthsurface at the nested joint, the load being distributed along thearcuate surfaces, where a portion of the load is transferred to adirection transverse to the nested joint.
 14. The method of claim 13,wherein the step of assembling is further defined as including the stepof applying a second fabric layer comprising at least one layer offabric onto said resulting first planar surface, and applying at leastone layer of fabric onto said resulting second surface.
 15. The methodof claim 13, wherein each of said preform panels is rectangular, andwherein said concave arcuate surface and said convex arcuate surface aredisposed upon opposing edges.
 16. The method of claim 14, wherein eachof said preform panels is rectangular, and wherein said concave arcuatesurface and said convex arcuate surface are disposed upon opposingedges.
 17. The method of claim 13, wherein said foam is further definedto be polyurethane foam.
 18. The method of claim 13, wherein said firstfabric layer is comprised of fibers selected from the group consistingof fiberglass, carbon fiber, and para-aramid synthetic fiber, andwherein said resin is selected from the group consisting of polymerresin, polyester resin, vinyl ester resin, polyurethane resin, epoxy,hybrid resin, and co-cured resin.
 19. The method of claim 13, whereinthe step of assembling is further defined as enclosing said plurality ofpreform panels in a mold, and wherein the step of wetting is furtherdefined as either injecting or infusing said resin into said mold. 20.The method of claim 13, wherein the step of assembling is furtherdefined as enclosing said plurality of preform panels in a vacuum bag,and wherein the step of curing is further defined as including the stepof reducing pressure inside the bag until the resin is cured.